Monday, December 13, 2010

LEGO Mindstorm!

Continuing with the improvement of our Chameleon Suit design, we've decided to implement the suit using LEGO Mindstorm components. Although our initial thoughts were to use Phidget sensors and motors, we soon found out that Servo motors are extremely limited in their range of motion, and are not very suitable for our design. Another problem with using Phidgets is that we need to somehow hook up a computer to the sensors and motors, which will add an enormous amount of bulk to our suit (thus not ideal). However, LEGO Mindstorm has this block-sized microcontroller that's as big as a bag of chips, which is not too bad compared to carrying an entire laptop computer on the suit. The Mindstorm kit also comes with pre-made sensors such as touch sensors, sound sensors, etc., which will be perfect for what we had in mind for input. And the best part is, their motors are programmable! So we can actually program a set number of rotations on the motors, and have it change direction and all with some simple codes ^___^.
LEGO Mindstorm sensors and motors

Although the size of the motors are a little bit larger than what I had in mind (compared to Phidgets motors and normal dc motors), the amount of customization available to the LEGO motors from the microcontroller makes up for it.
Size comparison of the different motors. From left to right: dc motor, LEGO Mindstorm motor, and Phidgets Servo motor.
Using the proposed LEGO Mindstorm motors, we constructed some sample structures of the skirt action. By using the rubber band waist of the skirt to hold up the motors, we managed to attach one motor to each side of the skirt. There's a spool on each motor that holds up a thin string, which connects to the bottom of the skirt.
However, we soon realized that with only two strings (one on each side), the skirt will not be pulled up evenly. A lot of fabric in the front and back of the skirt will just hang limp. Therefore we decided to attach an extra spool to each of the motors using a lot of LEGO connector pieces, and used a rubber band on the spools to connect them to each other. And the end result looked like this:
Two spools per motor, with the strings connecting to the left and right side of the skirt as well as the front and back of the skirt.
This implementation KIND OF worked. The skirts managed to get pulled up, but the fabrics looked bunched up together where the strings are, and it just basically didn't look aesthetically pleasing at all. Another problem is that now the size of the whole pulley system is ENORMOUS. We were thinking of making a extra large belt to cover up the motors...but that probably won't work out too well x__X.

So there's still a lot of bugs and problems to be fixed with the skirt, as well as implementing the movement structures for the sleeves and collars. 

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